I am researching to purchase a multi zone mini split system.I am going to purchase a 9 + 12 two zone system.The place I am looking at is selling a 9 + 12 with a 20,000 BTU outside condenser.Does the condenser unit BTU have to equal the indoor units? Meaning, shouldn't the outdoor unit be 21,000?

By the way, the also sell a 12 + 12 with the same 20,000 outdoor unit.

I'm confused.Any help is greatly appreciated before spending a lot of money.Thanks.

The EVAP BTU's can be under the condenser BTU's and go slightly over. I don't want to overstep but I would consult a local air conditioning contractor on the size required also. It shouldn't be guessed. Most equipment is not properly sized so replacing with the same may not give you optimum performance.